The present invention relates to a transfer paper separating device for use in an image forming apparatus, such as a copying machine, for forcibly separating transfer paper passed through an image transfer process from a surface of a photosensitive drum.
A generally known transfer paper separating device is provided with a separating claw always in contact with the surface of a photosensitive drum for separating transfer paper passed through the image transfer process from the drum surface.
Further, in such a transfer paper separating device, the separated transfer paper is likely to press the separating claw against the surface of the photosensitive drum, which consequently damages the drum surface. Also, the separated transfer paper is likely to be rolled up to more downstream of the drum surface. In order to prevent such likelihoods, a guide member is provided near the separating claw for guiding the separated transfer paper to a transport path right after the transfer paper is separated by the separating claw.
Conventionally, to support a separating claw and a guide member, it has been known that the separating claw and the guide member are attached to a common supporting shaft with juxtaposed with each other in an axial direction thereof.
In this common shaft supporting, there have been known the following two methods:
1) A constant contact method in which the tip of a separating claw is constantly in contact with a surface of a photosensitive drum; and
2) A pivotal method in which a separating claw is pivoted by a solenoid or other actuator integrally with the supporting shaft or independently thereof between an operative position in which the tip of the separating claw is in contact with a surface of a photosensitive drum and an inoperative position in which the tip of the separating claw is away from the drum surface.
However, according to the constant contact method, the tip of the separating claw is constantly pressed against the drum surface, thereby causing a large load on the drum surface in the long run. Further, the tip of the separating claw is more liable to be worn, shortening the replacement cycle of separating claws.
On the contrary, according to the pivotal method, the separating claw is away from the drum surface other than the time when necessary, such as when it is necessary to separate transfer paper. Accordingly, the load on the drum surface can be reduced. However, it is necessary to provide a mechanism for pivoting the separating claw. Further, it is very difficult to accurately regulate the separating claw pivoting mechanism so that the tip of the separating claw comes into contact with the drum surface with an appropriate pressure in the operative position. Accordingly, it is unavoidable that the tip of the separating claw comes into contact with the drum surface with exceedingly large pressure, causing a greater damage to the drum surface than the constant contact method.
In the common shaft supporting, further, the separating claw is slid from one end of the supporting shaft and fixedly attached to the supporting shaft by providing fixing members, such as E-rings, on both sides of the separating claw. Accordingly, it has been cumbersome to attach a separating claw to the supporting shaft.
Further, when an old separating claw is replaced with a new one due to wear in the tip of the old separating claw or other cause, the following three steps have caused an inefficient replacement of separating claws:
1) The supporting shaft is required to be dismounted from the transfer paper separating device to detach the old separating claw from the supporting shaft;
2) The fixing members are required to be removed from the supporting shaft to detach the old separating claw from the supporting shaft; and
3) The guide member stands as an obstacle when the old separating claw is detached.